WATCH: Military helicopters rescue thousands of people stranded by monsoon floods in Pakistan's northwest Khyber Pakhtunkhwa province. At least 400,000 people have been affected.

PESHAWAR -- Flashfloods triggered by heavy monsoon rains have wreaked havoc in northern Pakistan, leaving more than 400 people dead and hundreds of thousands stranded.

Strife-torn Khyber-Pakhtunkhwa Province and Pakistani Kashmir have been hardest hit during the three days of flooding.

The government of Pakistan's northwestern Khyber-Pakhtunkhwa Province has announced an emergency in the province and pleaded for assistance from the central government.

The province's information minister, Mian Iftikhar Hussain, told RFE/RL that all 24 districts of Khyber-Pakhtunkhwa have been affected by the rains and flashfloods.

"In fact, not a single district of the province is safe, both in the plain and mountainous areas. In our province, there was a historic flood in 1931, but this [inundation] is far more than that flood because the water at that time was [at a level of] 175,000 cusecs [cubic feet per second], but in the present situation, the water flow is 250,000 cusecs," Hussain said.

Hussain said most of his province's rain and flood-related casualties were reported from Swat. Sixty people have died so far in this scenic valley, which became a safe haven for Taliban after 2006.

"[In Swat], our infrastructure was destroyed by terrorists, and whatever was left was destroyed by the floods. So far 60 people have been killed and 400,000 are stranded," Hussain said.

"We are trying to evacuate them as the weather improves now and we can run a helicopter service. Even now, the biggest threat from floods is posed to [the Swat Valley's] Charsadda and Nowshera districts."Khyber Pass Closed

According to officials from Pakistan's meteorological office, the Khyber-Pakhtunkhwa province has received nearly 30 centimeters of rain in the past 36 hours, the highest in 35 years.

The Khyber Pass, the route connecting Peshawar with Afghanistan and the key route for NATO’s shipment convoys to Afghanistan through Pakistan, was also briefly closed, with hundreds of vehicles stranded along the zigzag 40-kilometer road.

Last week, similar rains lashed Pakistan’s southwestern Balochistan Province leaving over 50 dead. The floods affected a wide swath of the resource-rich but impoverished province, where Pakistani security forces are countering an ethnic Baloch insurgency.

Locals have complained about the pace of the relief effort. Muhammad Rahman, a resident of Swat, told Radio Mashaal that many of his relatives were stranded.

"There are around 11 houses of our relatives. Their houses were submerged in water last night and the residents then took refuge in a rest house on a hilltop. We were in contact with them until morning, but no one provided help. Now the water has reached the rest house and we have no telephone contact with them now," Rahman said.

Locals say they hope for help from the government and the army. Shams, a local resident who goes by one name, told Radio Mashaal that some army men had arrived in his area on July 29. But he said the rescue operation requires more personnel and equipment.

"The water level is higher. Some army people are here to help, but they have only one boat. We hear the cries of people in the houses where they are stranded. Many people have climbed trees. The men have fixed wooden beds in the trees and they have taken refuge there," Shams said.

Pakistan's meteorological office has predicted the present monsoon level rains will end within 24 hours.